Stable cationically crosslinkable/polymerizable dental composition with a high filler content

ABSTRACT

Stable and substantially filled cationic dental compositions are described which include: (1) at least one cationically reactive compound (A); (2) at least one dental filler (B); (3) optionally, at least one dispersant (C) composed of at least one organic polymer or copolymer; (4) at least one cationic photoinitiator (D); and (5) optionally, at least one photosensitizer (E). The dental filler (B) is treated with at least one organosilicon coupling agent (F), and at least one compound (G). The organosilicon coupling agent (F) has at least one reactive function (rfA) directly linked to a silicon atom forming after activation of a chemical bond with the dental filler, and at least one reactive function (rfB) not directly linked to a silicon atom, forming after activation, a chemical bond with a reactive function (rfC) of the compound (G).

The field of the invention is that of dental compositions. Morespecifically, the dental compositions developed in the context of thepresent invention may be used for making dental prostheses and fordental restoration.

These dental compositions are conventionally epoxy resins, orphotopolymerizable silicones or free-radical-polymerizable acrylateresins. These compositions also include particulate reinforcing fillers(e.g. hydrophobicized silica), photoinitiators and optionallyphotosensitizers or even other functional additives such as pigments orstabilizers.

Once mixed together, these compositions are shaped and thenphotocrosslinked into a mass whose structure is similar to that ofteeth.

The fact that the filler consists of very fine particles (a 0.01 to 5μm) with a large specific surface area is a factor that limits itsdegree of incorporation into the resin. The reason for this is that saidresin has a limited absorption capacity. As a result, the fillercontents of such compositions rarely reach more than 45% by volume. Thistherefore penalizes the mechanical reinforcing function assigned to theparticulate filler.

Furthermore, dental compositions are formulated with reinforcing fillerssuch as mineral glasses or combustion silicas of very low particle size,the surface silanols and/or residual water of which react with thecationic functions, preventing the compositions from being stored. Thisis also the case when these glasses or these combustion silicas arepretreated with silanes, for instance glycidyloxypropyltrimethoxysilaneor glycidyloxypropyltriethoxysilane, or evenmethacryloxypropyltrimethoxysilane. Reinforcing fillers interact withthe reactive functions of the (photo)polymerizable/crosslinkable speciesand are thus the cause of instability problems of the dental compositionduring its storage, which may be up to several months. This phenomenonof instability on storage is accentuated for substantially filledcompositions (i.e. overall filler content ≧50%).

U.S. Pat. No. 6,306,926 concerns dental compositions based on epoxyresins (e.g. UVR® 6105, EPON® 828, GY281®), oxetane or vinyl ether,inter alia, which are polymerizable/crosslinkable, cationically andunder irradiation, and optionally free-radical-polymerizable(meth)acrylate resins. Besides polymerization inducers such as cationicphotoinitiators and optionally free-radical initiators, depending on thecase, these compositions comprise a radio-opaque microparticulatemineral filler selected from the following metallic compounds: oxides,halides, borates, phosphates, silicates, carbonates, germanates,tetrafluoroborates, hexafluorophosphates, having an isoelectric point ofless than 7. This composition is such that its Barcol hardness is atleast 10, after 30 minutes of cationic polymerization at 25° C.

These resins have the drawback of not being fully transparent to theactinic radiation for activation of the polymerization via UV-visibleradiation, which is harmful to the reaction kinetics and thus limits thepossibilities of obtaining very thick photocrosslinked materials.

Patent application FR-A-2 784 025 is directed toward overcoming thisproblem by proposing dental compositions based on silicone resins thatare polymerizable/crosslinkable, cationically and under irradiation,possibly followed by thermal post-crosslinking. These silicone resinscontain oxirane (epoxide, oxetane, etc.) or vinyl ether functionalities.Such compositions comprise:

-   -   one or more cationically crosslinkable and/or polymerizable        polydimethylsiloxanes bearing on at least one of their ends        reactive functions of formula:    -   an effective amount of at least one initiator of onium borate        type:    -   at least one photosensitizer, and    -   at least one dental filler or inert reinforcing filler based on        dental glasses or on polymethyl methacrylate or on combustion        silica optionally treated with hexamethyldisilazane or        polydimethylsiloxane with a specific surface area of 200 m²/g.

These dental compositions are intended for the manufacture of dentalprostheses or appliances and for dental restoration.

These silicones have the advantage over cationically crosslinkingorganic resins of being highly transparent to UV-visible light and thusof allowing very thick (several millimeters thick) photocrosslinkedmaterials to be obtained in a very short time (less than one minute)with a UV lamp that emits in the visible range >400 nm.

However, these silicones are formulated with reinforcing fillers ofLewis acid or Brönsted acid nature, such as ground glasses or combustionsilicas of very low particle size, the surface silanols and/or theresidual water of which react with the cationic functions. Such siliconeformulations are therefore unstable on storage. Furthermore, when thesesilicones are formulated with photosensitizers of thioxanthone type,large chromatic variation is observed during exposure for crosslinkingpurposes. This is reflected by a pinkish coloration of the finishedproduct (after exposure) which is not esthetically desirable.

Besides these problems, these silicone dental compositions remain to beimproved as regards increasing the filler content, so as to allow animprovement in the mechanical properties.

Substantially filled dental compositions, presented as having goodmechanical properties and comprising from 10% to 70% by volume of filler(e.g. combustion silica) with a particle size (Dm) of between 0.05 and0.5 μm (less than 50% by volume of particles of diameter Φ>0.50 μm), afree-radical-photopolymerizable acrylic monomer and a dispersant ofphosphoric acid ester type of formula:R—[—CO—(CH₂)₅—O—]_(n)PO₃H₂are moreover known, through patent application EP-A-1 050 291.

Such a teaching relating to free-radical dental compositions cannot inany way be transposed to silicone-based cationic dental compositions.The reason for this is that the dispersants R—[—CO—(CH₂)₅—O—]_(n)PO₃H₂are not suitable for cationic compositions, especially since theycontain a large acidic residue RPO₃H₂ that reacts in the presence ofoxirane functions and harms the stability of the composition.

It is thus seen that the prior art does not provide a satisfactorysolution to the twofold problem of stability on storage of dentalcompositions based on units that are polymerizable cationically under UV(for example oxiranes) and of dispersion of large amounts of fillers inthe resin. Furthermore, the prior art does not provide a solution eitherto the problem of the residual coloration of dental compositions aftercrosslinking.

One of the essential objectives of the present invention is thus toovercome this by providing novel dental compositions based on units thatare polymerizable cationically under UV (for example oxiranes), which donot have the drawbacks of the prior art as regards the stability onstorage and the limited filler content.

Another essential objective of the present invention is to provide novelcationic dental compositions that are polymerizable and/or crosslinkablein an oral environment, which are not only stable on storage andsubstantially filled (e.g. ≧50%), but which also have the advantage ofbeing highly transparent to UV-visible light and thus of allowing verythick (several millimeters thick) photocrosslinked materials to beobtained in a very short time (less than one minute) with a UV lamp that-emits in the visible range >400 nm.

Another essential objective of the present invention is that ofproviding novel cationic dental compositions that are polymerizableand/or crosslinkable in an oral environment, which are stable,substantially filled (e.g. ≧50%), easy and economical to prepare, butalso which do not have the drawback of generating spurious colorationsafter crosslinking.

Another essential objective of the present invention is that ofproviding a novel process for treating a reinforcing filler, inparticular a dental reinforcing filler, such that it can satisfy theconstraints outlined above when it is used especially as a reinforcingfiller in a dental composition.

These objectives, among others, are achieved by the present invention,which relates firstly to a dental composition comprising:

-   -   (1) at least one cationically reactive compound (A);    -   (2) at least one dental filler (B);    -   (3) optionally at least one dispersant (C) comprising at least        one organic polymer or copolymer;    -   (4) at least one cationic photoinitiator (D);    -   (5) and optionally at least one photosensitizer (E),        said composition being characterized in that at least one dental        filler (B) is treated:    -   a) with at least one organosilicon coupling agent (F) and    -   b) with at least one compound (G),        said organosilicon coupling agent (F) comprising at least one        reactive function (rfA) directly linked to a silicon atom        reacting with the dental filler, and at least one reactive        function (rfB) not directly linked to a silicon atom, reacting        with a reactive function (rfC) of the compound (G).

In one preferred embodiment:

-   -   the reactive function (rfA) directly linked to a silicon atom of        the organosilicon coupling agent (F) is an alkoxy, enoxy or        hydroxyl function;    -   the reactive function (rfB) not directly linked to a silicon        atom of the organosilicon coupling agent (F) is an oxirane,        oxetane, hydroxyl, acid, carboxylic acid anhydride or diol        function; and    -   the reactive function (rfC) of the compound (G) is an oxirane,        oxetane, alkenyl ether or carbonate function.

The inventors have, to their credit, shown, surprisingly andunexpectedly, that it is possible to treat the surface of the filler andthus to increase the filler content and therefore to reinforce thematerial while at the same time improving the stability on storage ofthe composition. This stability is reflected by a shelf life of severalmonths or years.

This technical solution is all the more advantageous since it iseconomically viable and easy to implement.

It is also advantageous to note that this composition is satisfactory interms of limiting the shrinkage after polymerization/crosslinking, whichis entirely noteworthy in the dental application.

According to one preferred variant of the invention, the dentalcomposition according to the invention comprises at least one dentalfiller (B) treated via a process (I) comprising the following steps:

-   -   a) the dental filler (B) and at least one organosilicon coupling        agent (F) comprising at least one alkoxy and/or hydroxyl        function directly linked to a silicon atom and at least one        oxirane, oxetane, hydroxyl, acid, carboxylic acid anhydride        and/or diol function are mixed together in solvent medium,        preferably in aqueous medium,    -   b) the solvent is evaporated off to obtain an intermediate        dental filler (B-1),    -   c) the intermediate dental filler (B-1) undergoes a heat        treatment so as to allow the coupling reaction between the        intermediate dental filler (B-1) and the coupling agent (F) and        thus to obtain an intermediate dental filler (B-2),    -   d) the intermediate dental filler (B-2) is next mixed in solvent        medium with at least one compound (G) comprising at least one        oxirane, oxetane, alkenyl ether and/or carbonate function,    -   e) the solvent is evaporated off to obtain an intermediate        dental filler (B-3), and    -   f) the intermediate dental filler (B-3) undergoes a heat        treatment so as to allow the reaction between the intermediate        dental filler (B-3) and the compound (G) and thus to obtain a        treated dental filler (B-4).

According to another preferred variant of the invention, the heattreatment of steps c) and f) of the process (I) is performed by heatingto a temperature of less than or equal to 200° C., preferably less thanor equal to 165° C. and even more preferably of between 100 and 165° C.

According to one preferred embodiment, the overall content of dentalfillers (B) represents up to 85% by weight and preferably between 60%and 80% by weight relative to the total weight of the dentalcomposition.

Advantageously, the treatment of the dental filler (B) is performed withup to 20% by weight, preferably between 1% and 15% by weight and evenmore preferably between 2% and 10% by weight of the compound (G)relative to the total weight of the dental composition.

The treatment of the dental filler (B) with the organosilicon couplingagent (F) is preferably performed with compounds of formula:

in which formula:

-   -   R is a hydrogen or a linear or branched C1-C4 alkyl or alkenyl        radical,    -   R¹ is a linear or branched alkyl radical or a phenyl radical,    -   x is equal to 0, 1 or 2, and        X being defined by the following formula:        with:    -   E and D which are identical or different radicals chosen from        linear or branched C1-C12 alkyls,    -   z is equal to 0 or 1;    -   n is equal to 0 or 1;    -   is equal to 0, 1, 2, 3, 4, 5 or 6;    -   R², R³, R⁴, R⁵, R⁶, R⁷ and R⁸ are radicals, which may be        identical or different, representing a hydrogen atom or a linear        or branched C1-C12 alkyl.

Preferred organosilicon coupling agents (F) that may be mentionedinclude the following compounds: glycidyloxypropyltrimethoxysilane, theproduct of hydrolysis of glycidyloxypropyltrimethoxysilane;glycidyloxypropyltriethoxysilane, the product of hydrolysis in acidicmedium of glycidyloxypropyltriethoxysilane;glycidyloxypropyldimethoxymethylsilane or the hydrolysis product, thesilane β-(3,4-epoxycyclohexyl)ethyltriethoxysilane or the hydrolysisproduct, the silane β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane or thehydrolysis product.

The treatment of the dental filler (B) with the compound (G) ispreferably performed with a compound that is an organic monomer,oligomer or polymer or an organosiloxane comprising at least oneoxirane, oxetane, alkenyl ether and/or carbonate function and even morepreferably comprising at least one oxirane function.

Preferably, the compound (G) comprises at least one function chosen fromthe group consisting of the structures (M-7) to (M-12) below:

with R″ representing a linear or branched C₁-C₆ alkyl radical.

According to a first preferred embodiment, the compound (G) is asilicone oligomer (G-1) or a silicone polymer (G-2). The siliconeoligomer (G-1) and the silicone polymer (G-2) comprise:

-   -   a) at least one unit of formula:    -   in which formula:        -   a =0, 1 or 2,        -   R⁰, which may be identical or different, represents an            alkyl, cycloalkyl, aryl, vinyl, hydrogeno or alkoxy radical,            preferably a C1-C6 lower alkyl,        -   Z, which may be identical or different, is an organic            substituent comprising at least one oxirane, alkenyl ether,            oxetane and/or carbonate function, and    -   b) at least two silicon atoms.

Advantageously, the silicone oligomer (G-1) and the silicone polymer(G-2) are chosen from the group consisting of the compounds of formulae:

with L=H; OH; Me; Phenyl; C1-C12 Alkyl; C1-C6 Cycloalkyl; the groups

with n<100; a<100 and m<100

in which formulae R^(o) or R₀, which may be identical or different,represents an alkyl, cycloalkyl or aryl radical, preferably a C1-C6lower alkyl.

in which formulae the group D is a linear or branched C1-C12 alkyl and nis an integer between 1 and 20 (limits inclusive), with Ar=aryl group.

According to a second preferred embodiment, the compound (G) is a silane(G-3) of formula:

in which formula:

-   -   R, which may be identical or different, represents an alkyl,        cycloalkyl, aryl, vinyl, hydrogeno or alkoxy radical, preferably        a C1-C6 lower alkyl,    -   Z, which may be identical or different, is an organic        substituent comprising at least one oxirane, alkenyl ether,        oxetane and/or carbonate function, and        −a+b=3.

According to one preferred embodiment, the silane (G-3) is chosen fromthe group consisting of the molecules (S-93) to (S-95):

According to another preferred embodiment, the compound (G) is anorganic compound (G-4) chosen from the group consisting of the molecules(S-96) to (S-104):

in which formulae: n is an integer between 1 and 10 (limits inclusive),

with n<100 and D=linear or branched C1-C12 alkyl.

Among the molecules of the type (S-103), the resin UVR6150® sold by thecompany Dow Chemical may be chosen.

with n<100 and the group D=linear or branched C1-C12 alkyl.

For the resins of type (S-104), the one in which n=0 is particularlysuitable for the invention.

In general, the photochemical activation is performed under UVradiation. More particularly, a UV radiation with a wavelength of aboutfrom 200 to 500 nm is used for making dental prostheses and a UV-visibleradiation with a wavelength of greater than 400 nm is used for makingrestoration materials. A wavelength of greater than 400 nm allowscrosslinking and/or polymerization in an oral environment.

The actinic (photochemical) activation may advantageously be completed(or even replaced) with thermal activation.

Preferably, the cationically reactive compound (A) is chosen from thegroup of monomers and/or (co)polymers comprising:

-   -   epoxys, vinyl ethers, oxetanes, spiroorthocarbonates,        spiroorthoesters and combinations thereof.

Even more preferably, the cationically reactive compound (A) is asilicone oligomer (G-1), a silicone polymer (G-2), a silane (G-3) or anorganic compound (G-4) as defined above by the unit (M-13), or themolecules (S-1) to (S-101).

In formula (M-13), the reactive functions Z that are particularlyadvantageous comprise at least one reactive function chosen from thefollowing radicals:

-   -   with R″ representing a linear or branched C1-C6 alkyl radical.

According to one advantageous variant, the cationically reactivecompound (A) is combined with an organic epoxy resin or oxetanerepresenting less than 80% by mass of the fraction. Among the chosenfunctional organic resins that will be preferred are those for which themass percentage of reactive function is less than 20% and preferablyless than 15%. The volume shrinkage will be all the more reduced duringthe polymerization. The resins that will preferably be selected arethose of formulae (S-103) and (S-104):

with n<100 and D=linear or branched C1-C12 alkyl.

Among the resins of (S-103) type that may be chosen is the resinUVR6150® sold by the company Dow Chemical.

with n<100 and the group D=linear or branched C1-C12 alkyl.

For the resins of (S-104) type, the one in which n=0 is particularlysuitable for the invention.

Various types of dental filler (B) may be used to prepare thecompositions according to the invention. The fillers are chosen as afunction of the final use of the dental composition: these fillersaffect important properties such as the appearance, the penetration ofUV radiation, and also the mechanical and physical properties of thematerial obtained after crosslinking and/or polymerization of the dentalcomposition.

Reinforcing fillers that may be used include treated or untreatedpyrogenic silica fillers, amorphous silica fillers, quartz, glasses ornon-vitreous fillers based on silicon oxides, for example of the typedescribed in U.S. Pat. No. 6,297,181 (barium-free), zirconium, barium,calcium, fluorine, aluminum, titanium, zinc, borosilicates,aluminosilicates, talc, spherosil, ytterbium trifluoride, polymer-basedfillers in the form of ground powder such as inert or functionalizedpolymethyl methacrylates, polyepoxides or polycarbonates, ceramicwhiskers (Si—C, Si—O—C, Si—N, Si—N—C, Si—N—C—O) and glass fibers.

Examples that will be mentioned include:

-   -   inert fillers based on polymethyl methacrylate Luxaself® from        the company UGL, which may be used in the dental field and        pigmented pink,    -   combustion silica fillers treated with hexamethyldisilazane or        polydimethylsiloxane, with a specific surface area of 200 m²/g,    -   untreated combustion silica fillers (Aerosil-AE200® sold by the        company Degussa),    -   quartz or glasses based on silicon oxides.

According to one embodiment of the invention, the dental filler (B) is amineral glass or a combustion silica.

According to one advantageous characteristic of the invention, thedental fillers (B) represent up to 85% by weight, preferably between 50%and 85% by weight and even more preferably between 60% and 85% by weightrelative to the total weight of the dental composition.

In accordance with the invention, the dispersant (C) is selected fromthe group comprising: polyurethane/acrylate copolymers optionallysalified with an alkylammonium, acrylic copolymers optionally salifiedwith an alkylammonium, carboxylic acid monodiesters, polyesters,polyethers, polyurethanes, modified polyurethanes, polyol-polyacrylates,copolymers thereof or mixtures thereof. The dispersants sold under thebrand name Disperbyk® (from the company Byk) or Solspers® (from thecompany Avecia) are particularly suitable for the invention. Examplesthat may be mentioned in particular include the commercial products:Disperbyk® 164, Disperbyk® 161, Disperbyk® 166, Disperbyk® 2070,Disperbyk® 9075, Disperbyk® 9076. Mention may also be made of thedispersants cited in the following patents:

-   -   U.S. Pat. No. 5,882,393 describing dispersants based on        polyurethanes/imidazoles-acrylates or epoxides;    -   U.S. Pat. No. 5,425,900 describing polyurethane-based        dispersants;    -   U.S. Pat. No. 4,795,796 describing dispersants based on        polyurethanes/polyoxyalkylene glycol monoalkyl ether;    -   patent application WO-A-99/56864 describing dispersants based on        polyurethanes/poly(oxy-alkylene-carbonyl): ε-caprolactone and        δ-valero-lactone derivatives; and    -   patent EP-B-0 403 197 describing dispersants of grafted        polyol-polyacrylate type comprising a        polyurethane/polyvinyl/polyacrylate random copolymer and a        polyoxyalkylene polyether.

Quantitatively speaking, the dispersant (C) is present in a proportionof from 50 ppm to 1% and preferably 100 ppm to 5000 ppm.

Preferably, the amine number of the dispersant (C) is less than or equalto 60 and even more preferably between 0.1 and 50 mg of potassiumhydroxide per gram of dispersant (C).

Advantageously, the acid number of the dispersant is less than or equalto 200, preferably less than or equal to 100 and even more preferablybetween 1 and 60 mg of potassium hydroxide per gram of dispersant.

The cationic photoinitiators (D) are chosen from onium borates (takenalone or as a mixture) of an element from groups 15 to 17 of thePeriodic Table [Chem. & Eng. News, vol. 63, No. 5, 26 of Feb. 4, 1985]or of an organometallic complex of an element from groups 4 to 10 of thePeriodic Table [same reference].

According to one preferred mode, the cationic photoinitiator (D) is ofborate type and is chosen from those in which:

-   -   a) the cationic species of the borate is selected from:    -   (1) the onium salts of formula:        ([R⁹)_(n)−A−(R¹⁰)_(m)]⁺  (I)    -   in which formula:        -   A represents an element from groups 15 to 17, for instance:            I, S, Se, P or N,        -   R⁹ represents a C6-C20 carbocyclic or heterocyclic aryl            radical, said heterocyclic radical possibly containing            nitrogen or sulfur as hetero elements,        -   R¹⁰ represents R⁹ or a linear or branched C1-C30 alkyl or            alkenyl radical; said radicals R⁹ and R¹⁰ being optionally            substituted with a C1-C25 alkoxy, C1-C25 alkyl, nitro,            chloro, bromo, cyano, carboxyl, ester or mercapto group,        -   m and n are integers, with n+m=v+1, v being the valency of            the element A,    -   (2) oxoisothiochromanium salts, in the present case those        described in patent application WO 90/11303, especially the        sulfonium salt of 2-ethyl-4-oxoisothiochromanium or of        2-dodecyl-4-oxo-isothiochromanium and the oxoisothiochromanium        salts of structural formula V:    -   in which formula:        -   A represents        -   n1=an integer between 1 and 3;        -   z1=an integer between 0 and 3;        -   X represents a group of formula M¹Y¹ _(r1) (1) or of formula            Q¹ (2) in which M¹Y¹ _(r1) (1): M¹=Sb, As, P, B or Cl, Y¹            represents a halogen (preferably F or Cl) or 0 and in which            r1 is an integer between 4 and 6, the formula Q¹ (2)            represents a sulfonic acid        -   R⁸¹—SO₃ in which R⁸¹ is an alkyl or aryl group, or an alkyl            or aryl group substituted with a halogen, preferably F or            Cl,        -   R¹⁰¹ represents an alkyl or cycloalkyl group, preferably of            C₁-C₂₀, or an aryl group,        -   R²¹ represents a hydrogen or an alkyl, alkenyl, cycloalkenyl            or cycloalkyl group, preferably of C₁-C₂₀, or an aryl group,            all the R²¹ being independent of each other,        -   R³¹ represents a hydrogen or an alkyl, alkenyl, cycloalkenyl            or cycloalkyl group, preferably of C₁-C₂₀, or an aryl group,            all the R³¹ being independent of each other,        -   R⁴¹ represents a hydrogen, a halogen, an alkenyl group, for            example vinyl, cycloalkenyl, alkyl or cycloalkyl, preferably            of C₁-C₂₀, an alkoxy or thioalkoxy group, preferably of            C₁-C₂₀, a poly(alkylene oxide) group with up to 10 alkylene            oxide units ending with a hydroxyl or a (C₁-C₁₂) alkyl, an            aryl group or an aryloxy or thioaryloxy group,        -   R⁵¹ represents a halogen, an alkenyl group, for example            vinyl, cycloalkenyl, alkyl or cycloalkyl group, preferably            of C₁-C₂₀, an alkoxy or thioalkoxy group, preferably of            C₁-C₂₀, a poly(alkylene oxide) group with up to 10 alkylene            oxide units ending with a hydroxyl or a (C₁-C₁₂) alkyl, an            aryl group or an aryloxy or thioaryloxy group,        -   R⁶¹ represents a hydrogen, an alkyl, alkenyl, cycloalkenyl            or cycloalkyl group, preferably of C₁-C₂₀, or an aryl group,        -   R⁷¹ represents a hydrogen, an alkyl, alkenyl, cycloalkenyl            or cycloalkyl group, preferably of C₁-C₂₀, or an aryl group;            and    -   (3) the organometallic salts having the following formula:        (L₁L₂L₃M)^(+q)   (II)    -   in which formula:        -   M represents a metal from groups 4 to 10, especially iron,            manganese, chromium or cobalt,        -   L1 represents a ligand linked to the metal M via π            electrons, the ligand being chosen from the ligands            η³-alkyl, η⁵-cyclopentadienyl and η⁷-cycloheptatrienyl and            the η⁶-aromatic compounds chosen from the optionally            substituted η⁶-benzene ligands and the compounds containing            from 2 to 4 fused rings, each ring being capable of            contributing to the valency layer of the metal M via 3 to 8            π electrons,        -   L2 represents a ligand linked to the metal M via π            electrons, the ligand being chosen from the            η⁷-cycloheptatrienyl ligands and the η⁶-aromatic compounds            chosen from the optionally substituted η⁶-benzene ligands            and the compounds containing from 2 to 4 fused rings, each            ring being capable of contributing to the valency layer of            the metal M via 6 or 7 π electrons,        -   L3 represents from 0 to 3 identical or different ligands            linked to the metal M via a electrons, this or these            ligand(s) being chosen from CO and NO2+; the total            electronic charge q of the complex toward which L1, L2 and            L3 contribute and the ionic charge of the metal M being            positive and equal to 1 or 2; and    -   b) those in which the anionic borate species has the formula:        [BX_(a)R_(b)]⁻  (III)    -   in which formula:        -   a and b are integers ranging for a from 0 to 3 and for b            from 1 to 4 with a +b=4,        -   the symbols X represent:            -   a halogen atom (chlorine or fluorine) with a=0 to 3, or            -   an OH function with a=0 to 2,        -   the symbols R are identical or different and represent:            -   a phenyl radical substituted with at least one                electron-withdrawing group, for instance OCF₃, CF₃, NO₂                or CN, and/or with at least 2 halogen atoms (most                particularly fluorine), this being the case when the                cationic species is an onium of an element from groups                15 to 17,            -   a phenyl radical substituted with at least one element                or an electron-withdrawing group, especially a halogen                atom (most particularly fluorine), CF₃, OCF₃, NO₂ or CN,                this being the case when the cationic species is an                organometallic complex of an element from groups 4 to                10, or            -   an aryl radical containing at least two aromatic nuclei,                for instance biphenyl or naphthyl, optionally                substituted with at least one element or an                electron-withdrawing group, especially a halogen atom                including fluorine, in particular, OCF₃, CF₃, NO₂ or CN,                irrespective of the cationic species.

Without being limiting in nature, further details regarding thesubclasses of onium borate and of borate of organometallic salts thatare more particularly preferred in the context of the use in accordancewith the invention are given hereinbelow.

According to a first preferred variant of the invention, the anionicborate species that are most particularly suitable are the following:1′: [B(C₆F₅)₄]⁻ 2′: [(C₆F₅)₂BF₂]⁻ 3′: [B(C₆H₄CF₃)₄]⁻ 4′:[B(C₆F₄OCF₃)₄]⁻. 5′: [B(C₆H₃(CF₃)₂)₄]⁻ 6′: [B(C₆H₃F₂)₄]⁻ 7′: [C₆F₅BF₃]⁻

According to a second preferred variant of the invention, the oniumsalts of formula (S-26) that may be used are described in manydocuments, especially in patents U.S. Pat. Nos. 4,026,705, 4,032,673,4,069,056, 4,136,102 and 4,173,476. Among these, the following cationswill be most particularly preferred:

-   -   [(C₈H₁₇)—O—(C₆H₄)—I—C₆H₅)]⁺; [C₁₂H₂₅—(C₆H₄)—I—C₆H₅]⁺;        [(C₈H₁₇—O—(C₆H₄))₂I]⁺[(C₈H₁₇)—O—(C₆H₄)—I—C₆H₅)]⁺;        [(C₆H₅)₂S—(C₆H₄)—O—C₈H₁₇]⁺; [CH₃—C₆H₄—I—C₆H₄—CH₂CH(CH₃)₂]⁺;        [(C₁₂H₂₅—(C₆H₄)—I—(C₆H₄)—CH—(CH₃)₂]⁺[(C₁₂H₂₅—C₆H₄)₂I]⁺; [(C₆H₅)₃        S]⁺; [CH₃—(C₆H₄)—I—(C₆H₄)—CH(CH₃)₂]⁺(η5-cyclopentadienyl)        (η6-toluene)Fe⁺; (η5-cyclopentadienyl) (η6-cumene)Fe⁺,        (η5-cyclopentadienyl) (η6-methyl-1-naphthalene)Fe⁺;    -   [(C₆H₅)—S—C₆H₄—S—(C₆H₅)₂]⁺; [(CH₃—(C₆H₄)—I—(C₆H₄)—OC₂H₅]⁺;        (C_(n)H_(2n+1)—C₆H₄)₂I]⁺ (with, for the group C_(n)H_(2n+1), n=1        to 18 is linear or branched).

According to a third preferred variant, the organometallic salts (3) offormula (S-27) that may be used are described in documents U.S. Pat.Nos. 4,973,722, 4,992,572, EP-A-203 829, EP-A-323 584 and EP-A-354 181.The organometallic salts more readily selected according to theinvention are especially:

-   -   (η⁵-cyclopentadienyl) (η⁶-toluene)Fe⁺,    -   (η⁵-cyclopentadienyl) (η⁶-methyl-1-naphthalene)Fe⁺,    -   (η⁵-cyclopentadienyl) (β⁶-cumene)Fe⁺,    -   bis(η⁶-mesitylene)Fe⁺,    -   bis (η⁶-benzene)Cr⁺

In accordance with these three preferred variants, examples ofphotoinitiators of the onium borate type that may be mentioned includethe following products:

-   -   (P-16): [(C8H₁₇)—O—C₆H₄—I—C₆H₅)]⁺, [B(C₆F₅)]⁻;    -   (P-17): [C₁₂H₂₅—C₆H₄—I—C₆H₅]⁺, [B(C₆F₅)₄]⁻;    -   (P-18): [(C₈H₁₇—O—C₆H₄)₂I]⁺, [B(C₆F₅)₄]⁻;    -   (P-19): [(C₈H₁₇)—O—C₆H₄—I—C₆H₅)]⁺, [B(C₆F₅)₄]⁻;    -   (P-20): [(C₆H₅)₂S—C₆H₄—O—CBH₁₇]⁺, [B(C₆H₄CF₃)₄]⁻;    -   (P-21): [(C₁₂H₂₅—C₆H₄)₂I]⁺, [B(C₆F₅)₄]⁻;    -   (P-22): [CH₃—C₆H₄—I—C₆H₄—CH(CH₃)₂]⁺, [B(C₆F₅)₄]⁻;    -   (P-23): (η5-cyclopentadienyl)(η6-toluene)Fe⁺, [B (C₆F₅)₄]⁻;    -   (P-24): (η5-cyclopentadienyl)(η6-methyl-1-naphthalene)Fe⁺,        [B(C₆F₅)₄]⁻;    -   (P-25): (η5-cyclopentadienyl)(η6-cumene)Fe⁺, [B (C₆F₅)₄]⁻;    -   (P-26): [C₁₂H₂₅—C₆H₄)₂I]⁺, [B(C₆H₃(CF₃)₂]⁻;    -   (P-27): [CH₃—C₆H₄—I—C₆H₄—CH₂CH(CH₃)₂]⁺, [B(C₆F₅)₄]⁻;    -   (P-28): [CH₃—C₆H₄)—I—C₆H₄—CH₂CH(CH₃)₂]⁺, [B(C₆H₃ (CF₃)₂)₄]⁻; and    -   (P-29): [CH₃—C₆H₄—I—C₆H₄—CH(CH₃)₂]⁺, [B(C₆H₃(CF₃)₂)₄]⁻.

As another literature reference for defining the onium borates (1) and(2) and the borates of organometallic salts (3), mention may be made ofall of the content of patent applications EP 0 562 897 and 0 562 922.This content is incorporated in its entirety into the presentdescription by reference.

As another example of an onium salt that may be used as photoinitiator,mention may be made of those disclosed in patents U.S. Pat. Nos.4,138,255 and 4,310,469.

It is also possible to use other cationic photoinitiators, e.g.:

-   -   iodonium hexafluorophosphate or hexafluoroantimonate salts, such        as:        -   —[CH₃—[(C₆H₄)—I—[(C₆H₄)—CH(CH₃)₂]⁺[PF₆]⁻;        -   —[CH₃—(C₆H₄)—I—(C₆H₄)—CH₂CH(CH₃)₂]⁺[PF₆]⁻;        -   —[(C₁₂H₂₅—C₆H₄)₂I]⁺[PF₆]⁻ or    -   the ferrocenium salts of these various anions.

The photosensitizer contained within the dental composition according tothe invention may be of very varied nature. In the context of theinvention, it corresponds especially to one of the formulae (IV) to(XXIV) below:

in which:

-   -   when n=1, Ar¹ represents an aryl radical containing from 6 to 18        carbon atoms, a tetrahydronaphthyl, thienyl, pyridyl or furyl        radical or a phenyl radical bearing one or more substituents        chosen from the group consisting of F, Cl, Br, CN, OH, linear or        branched C₁-C₁₂ alkyls, —CF³, —OR¹³, —OPhenyl, —SR¹³, —SPhenyl,        —SO₂Phenyl, —COOR¹³, —O—(CH₂—CH═CH₂), —O(CH₂H₄—O)_(m)—H,        —O(C₃H₆O)_(m)—H, m being between 1 and 100,    -   when n=2, Ar¹ represents a C₆-C₁₂ arylene radical or a        phenylene-T-phenylene radical, in which T represents —O—, —S—,        —SO₂— or —CH₂—,    -   X represents a group —OR¹⁴ or —OSiR¹⁵ (R¹⁶ )₂ or forms, with        R¹¹, a group —O—CH(R¹⁷⁾—,    -   R¹¹ represents a linear or branched C₁-C₈ alkyl radical that is        unsubstituted or that bears a group —OH, —OR¹³, C₂-C₈ acyloxy,        —CF³ or —CN, a C₃ or C₄ alkenyl radical, a C₆ to C₁₈ aryl        radical or a C₇ to C₉ phenylalkyl radical,    -   R¹² has one of the meanings given for R¹¹ or represents a        radical —CH₂CH₂R¹⁸, or alternatively forms with R¹¹ a C₂-C₈        alkylene radical or a C₃-C₉ oxa-alkylene or aza-alkylene        radical,    -   R¹³ represents a lower alkyl radical containing from 1 to 12        carbon atoms,    -   R¹⁴ represents a hydrogen atom, a C₁-C₁₂ alkyl radical, a C₂-C₆        alkyl radical bearing a group —OH, —OR¹³ or CN, a C₃-C₆ alkenyl        radical, a cyclohexyl or benzyl radical, a phenyl radical        optionally substituted with a chlorine atom or a linear or        branched C₁-C₁₂ alkyl radical, or a 2-tetrahydropyranyl radical,    -   R¹⁵ and R¹⁶ are identical or different and each represent a        C₁-C₄ alkyl radical or a phenyl radical,    -   R¹⁷ represents a hydrogen atom, a C₁-C₈ alkyl radical or a        phenyl radical,    -   R¹⁹ represents a radical —CONH₂, —CONHR¹³, —CON(R¹³ )₂,        —P(O)(OR¹³ )₂ or 2-pyridyl:        in which:    -   Ar² has the same meaning as Ar¹ of formula (IV) when n=1,    -   R¹⁹ represents a radical chosen from the group consisting of a        radical Ar², a linear or branched C₁-C₁₂ alkyl radical, a C₆-C₁₂        cycloalkyl radical and a cycloalkyl radical forming a C₆-C₁₂        ring with the carbon of the ketone or a carbon of the radical        Ar², these radicals possibly being substituted with one or more        substituents chosen from the group consisting of —F, —Cl, —Br,        —CN, —OH, —CF₃, —OR¹³, —SR¹³, —COOR¹³, linear or branched C₁-C₁₂        alkyl radicals optionally bearing a group —OH, —OR¹³ and/or —CN,        and linear or branched C₁-C₈ alkenyl radicals;        in which:    -   R¹², which may be identical or different, have the same meanings        as in formula (IV),    -   Y, which may be identical or different, represent X and/or R⁴,    -   Z represents:        -   a direct bond,        -   a C₁-C₆ divalent alkylene radical, or a phenylene,            diphenylene or phenylene-T-phenylene radical (T: linear or            branched C₁-C₁₂ alkyl), or alternatively forms, with the two            substituents R¹² and the two carbon atoms bearing these            substituents, a cyclopentane or cyclohexane nucleus,    -   a divalent group —O—R¹⁹—O—, —O—SiR¹⁵R¹⁶—O—SiR¹⁵R¹⁶—O—, or        —O—SiR¹⁵R¹⁶—O—,    -   R²⁰ represents a C₂-C₈ alkylene, C₄-C₆ alkenylene or xylylene        radical,    -   or alternatively the species:        corresponds to —O—O—    -   and Ar⁴ has the same meaning as Ar¹ of formula (IV) when n=1.    -   the thioxanthone family of formula (VII):    -   m=0 to 8,    -   R²¹, which may be identical or different substituents on the        aromatic nucleus (nuclei), represent a linear or branched C₁-C₁₂        alkyl radical, a C₆-C₁₂ cycloalkyl radical, a radical Ar¹, a        halogen atom or a group —OH, —OR¹³, —CN, —NO₂, —COR¹³, —OCOR¹³,        —N(R¹³)₂, —O—R¹³—(NR¹³)₂—CHO, —O-phenyl, —CF₃, —SR¹³, —S-phenyl,        —SO₂-phenyl, —O-alkenyl or —Si(R¹³)₃.    -   the xanthene family of formula (VIII):    -   n=0 to 8    -   the xanthone family of formula (IX):    -   p=0 to 8    -   the naphthalene family of formula (X):    -   q=0 to 8    -   the anthracene family of formula (XI):    -   r=0 to 10    -   the phenanthrene family of formula (XII):    -   s=0 to 10    -   the pyrene family of formula (XIII):    -   t=0 to 10    -   the fluorene family of formula (XIV):    -   u=0 to 9    -   the fluoranthene family of formula (XV):    -   v=0 to 10    -   the chrysene family of formula (XVI):    -   w=0 to 12    -   the fluorone family of formula (XVII):    -   with x=0 to 8, for example 2,7-dinitro-9-fluorenone,    -   the chromone family of formula (XVIII):    -   with y=0 to 6    -   the eosin family of formula (XIX):    -   with z=0 to 5 with z=0 to 6    -   the erythrosin family of formula (XX):    -   with z=0 to 2 or 0 to 3    -   the erythrosin family of formula (XXI):    -   with z=0 to 3    -   the biscoumarin family of formula (XXII):    -   with x=0 to 8    -   the thioxanthone family of formula (XXIII):    -   with y=0 to 6    -   the thioxanthone family of formula (XXIV):    -   wity y=0 to 6

For formulae (VIII) to (XXIII), the group R²¹ has the same definition asfor the molecule (VII).

Other sensitizers may be used. It is especially possible to use thephotosensitizers described in documents U.S. Pat. Nos. 4,939,069;4,278,751; 4,147,552 and also the group consisting of the compounds ofthe coumarin, conjugated diketone, fluorone, amino ketone andpara-aminostyryl ketone family, and also mixtures thereof.

According to one preferred mode, the photosensitizer (E) is chosen fromthe group consisting of compounds of the anthracene, thioxanthone,camphorquinone and phenanthrenequinone class, and also mixtures thereof.

According to another preferred mode, the dental composition comprises asphotosensitizer (E) a salt of a thioxanthone substituted with at leastone group comprising an ammonium function. The use of this type ofphotosensitizer has the advantage of avoiding spurious colorations whenthe dental composition is crosslinked for the manufacture of a dentalprosthesis.

According to a first variant of the invention, the associated anion ofthe salt of the thioxanthone substituted with at least one groupcomprising an ammonium function is chosen from the following anions:

-   -   a halide, BF₄ ⁻, PF6⁻; SbF₆ ⁻; the anion (III) of formula        [BX_(a)R_(b)]⁻ as defined above, R_(f)SO₃ ⁻; (R_(f)SO₂)₃C⁻ or        (R_(f)SO₂)₂N⁻ with R_(f) being a linear or branched alkyl        radical substituted with at least one halogen atom, preferably a        fluorine atom.

According to a second variant of the invention, the photosensitizer (E),optionally in combination with at least one camphorquinone, aphenanthrenequinone and/or a substituted anthracene, has the formula:

in which formula:

-   -   R²² and R²³ are identical or different and represent a hydrogen        or an optionally substituted C1-C10 alkyl radical, and        preferably R22=R23=methyl,    -   (X⁻) being an anionic species, preferably a halide; BF₄ ⁻, PF₆        ⁻; SbF₆ ⁻; the anion (III) of formula [BX_(a)R_(b)]⁻ defined as        above, R_(f)SO₃ ⁻; (R_(f)SO₂)₃C⁻ or (R_(f)SO₂)₂N⁻, with R_(f)        being a linear or branched alkyl radical substituted with at        least one halogen atom, preferably a fluorine atom,    -   and even more preferably (X⁻) is chosen from the borates having        the following formulae: [B(C₆H₃(CF₃)₂)₄]⁻ and [B(C₆F₅)₄]⁻.

According to one preferred mode, the photosensitizer (E), optionally incombination with at least one camphorquinone, a phenanthrenequinoneand/or a substituted anthracene, has the formula:

In the context of the present invention, the photosensitizers have aresidual absorption of UV light of between 200 and 500 nm and preferably400 to 500 nm for the preparation of dental prostheses. For dentalrestoration, a photosensitizer with a residual absorption of UV light ofabove 400 nm will be preferred.

According to one preferred variant, the photosensitizers will be chosenfrom those of the families (VII), (X), (XI), (XIII), (XXIII), (XXIV) and(XXV). According to another embodiment, the photosensitizer is chosenfrom the group consisting of the following compounds:

-   -   (PS-30):        3-(3,4-dimethyl-9-oxo-9-thioxanthenen-2-yl-oxy)-2-hydroxypropyl)trimethylammonium        chloride;    -   (PS-31):        3-(3,4-dimethyl-9-oxo-9-thioxanthenen-2-yl-oxy)-2-hydroxypropyl)trimethylammonium        tetrakis(pentafluorophenyl)borate;    -   (PS-32):        3-(3,4-dimethyl-9-oxo-9-thioxanthenen-2-yl-oxy)-2-hydroxypropyl)trimethylammonium        tetrakis(bis-(trifluoromethyl)phenyl)borate;    -   (PS-33): phenanthrenequinone;    -   (PS-34): camphorquinone;    -   (PS-35): acenaphthenequinone;    -   (PS-36): dibenzoyl peroxide;    -   (PS-37): 2-ethyl-9,10-dimethoxyanthracene;    -   (PS-38): 9,10-diethoxyanthracene;    -   (PS-39): 9,10-dibutoxyanthracene;    -   (PS-40): 9-hydroxymethylanthracene;    -   (PS-41): 2-dimethylaminothioxanthone;    -   (PS-42): 3-ethylcarboxy-7-methoxythioxanthone;    -   (PS-43): 1-phenylthio-4-propoxythioxanthone;    -   (PS-44): 2-methoxythioxanthone;    -   (PS-45): 2-(N,N-diethylaminopropoxy)thioxanthone;    -   (PS-46): 2-isopropylthioxanthone;    -   (PS-47): 1-chloro-4-propoxythioxanthone;    -   (PS-48): 4-isopropylthioxanthone;    -   and mixtures thereof.

In the context of the invention, the stability on storage, themechanical strength, the modulus of elasticity and the compressionstrength of the material obtained after crosslinking are markedlyimproved. When the thioxanthones of the family described by formula(XXV) are used, an additional advantage is observed in using thethioxanthones (PS-31) or (PS-32), optionally in combination with atleast one camphorquinone, a phenanthrenequinone and/or a substitutedanthracene, namely the absence of residual coloration.

Besides the reinforcing fillers, pigments may be used to color thedental composition according to the envisioned use and the ethnicgroups.

For example, red pigments in the presence of microfibers are used fordental compositions used for the preparation of dental prostheses inorder to simulate the blood vessels.

Pigments based on metal oxides (iron oxide and/or titanium oxide and/oraluminum oxide and/or zirconium oxide, etc.) are also used for thedental compositions used for the preparation of restoration material, inorder to obtain a crosslinked material of ivory color.

Other additives may be incorporated into the dental compositionsaccording to the invention. For example, biocides, stabilizers, flavoragents, plasticizers and adhesion promoters.

Among the additives that may be envisioned, crosslinkable and/orpolymerizable coreagents of organic type will advantageously be used.These coreagents are liquid at room temperature or thermofusible at atemperature below 100° C., and each coreagent comprises at least tworeactive functions such as oxetane-alkoxy, oxetane-hydroxyl,oxetane-alkoxysilyl, carboxy-oxetane, oxetane-oxetane, alkenylether-hydroxyl, alkenyl ether-alkoxysilyl, epoxy-alkoxy,epoxy-alkoxysilyl, dioxolane-dioxolane-alcohol, etc. Examples that maybe mentioned include the resins R70 and R71.

The dental compositions according to the invention may be used fornumerous dental applications, and in particular in the field of dentalprostheses, in the field of dental restoration and in the field oftemporary teeth.

The dental composition according to the invention is preferably in theform of a single product containing the various components(“monocomponent”), which facilitates its implementation, especially inthe field of dental prostheses. Optionally, the stability of thisproduct may be ensured by organic derivatives containing amine functionsaccording to the teaching of document WO 98/07798.

In the field of dental prostheses, the product in the “monocomponent”form may be deposited using a syringe directly onto the plaster model orinto a key. Next, it is polymerized (polymerization by possiblesuccessive layers) using a UV lamp (visible light spectrum 400 to 500nm).

In general, it is possible to make a durable and esthetic dentalprosthesis in 10 to 15 minutes.

It should be noted that the products obtained using the dentalcomposition according to the invention are non-porous. Thus, afteroptional polishing using a felt brush, for example, the surface of thedental prostheses obtained is smooth and shiny and it is thereforeunnecessary to use varnish.

The applications in the field of dental prostheses are essentially thoseof the removable prosthesis, which may be divided into two types:

-   -   total prosthesis in the case of a patient who has had all his        teeth removed;    -   partial prosthesis due to the absence of several teeth,        reflected either by a temporary prosthesis or a skeleton        denture.

In the field of dental restoration, the dental composition according tothe invention may be used as material for stopping the front and backteeth in different shades (for example “VITA” shades), which is quickand easy to use.

Since the dental composition is nontoxic and polymerizable in thicklayers, it is not essential to polymerize the material in successivelayers. In general, a single injection of the dental composition issufficient.

The preparations for dental prostheses and for restoration materials aremade according to the usual techniques of the art.

In the case of application of the dental composition to a tooth, eitherthe tooth may be pretreated with an acid etch and then with anattachment primer, which may itself be photocrosslinkable, or the dentalcomposition may be prepared as a mixture with an attachment primerbefore its use.

The invention also relates to a process for treating a reinforcingfiller, in particular a dental reinforcing filler, characterized in thatthe filler is treated:

-   -   a) with at least one organosilicon coupling agent (F), and    -   b) with at least one compound (G),        said organosilicon coupling agent (F) comprising at least one        reactive function (rfA) directly linked to a silicon atom        reacting with the dental filler, and at least one reactive        function (rfB) not directly linked to a silicon atom reacting        with a reactive function (rfC) of the compound (G).

According to one preferred mode of the process according to theinvention:

-   -   the reactive function (rfA) directly linked to a silicon atom of        the organosilicon coupling agent (F) is an alkoxy, enoxy and/or        hydroxyl function;    -   the reactive function (rfB) not directly linked to a silicon        atom of the organosilicon coupling agent (F) is an oxirane,        oxetane, hydroxyl, acid, carboxylic acid anhydride or diol        function; and    -   the reactive function (rfC) of the compound (G) is an oxirane,        oxetane, alkenyl ether or carbonate function.

According to another embodiment, the filler is treated:

-   -   a) with at least one organosilicon coupling agent (F) comprising        at least one alkoxy and/or hydroxyl function directly linked to        a silicon atom and to at least one oxirane, oxetane, hydroxyl        and/or diol function; and    -   b) with at least one compound (G) comprising at least one        oxirane, oxetane, alkenyl ether and/or carbonate function.

The process according to the invention is particularly suitable fortreating a dental filler. This process (I) comprises the followingsteps:

-   -   a) the dental filler (B) and at least one organosilicon coupling        agent (F) comprising at least one alkoxy and/or hydroxyl        function directly linked to a silicon atom and to at least one        oxirane, oxetane, hydroxyl and/or diol function, are mixed        together in solvent medium,    -   b) the solvent is evaporated off to obtain an intermediate        dental filler (B-1),    -   c) the intermediate dental filler (B-1) is subjected to a heat        treatment so as to allow the coupling reaction between the        intermediate dental filler (B-1) and the coupling agent (F) and        thus to obtain an intermediate dental filler (B-2),    -   d) the intermediate dental filler (B-2) is then mixed in solvent        medium with at least one compound (G) comprising at least one        oxirane, oxetane, alkenyl ether and/or carbonate function,    -   e) the solvent is evaporated off to obtain an intermediate        dental filler (B-3), and    -   f) the intermediate dental filler (B-3) is subjected to a heat        treatment so as to allow the reaction between the intermediate        dental filler (B-3) and compound (G) and thus to obtain a        treated dental filler (B-4).

According to one preferred mode, the heat treatment of steps c) and f)of the process (I) is performed by heating to a temperature of less thanor equal to 200° C., preferably less than or equal to 160° C. and evenmore preferably of between 100° C. and 165° C.

The organosilicon coupling agent (F), the compound (G) and the dentalreinforcing filler (B) are as defined in the dental compositionaccording to the invention.

The invention also relates to a reinforcing filler obtained via theprocess according to the invention.

The Examples and Tests below are given for illustrative purposes. Theyespecially allow the invention to be understood more clearly and allowsome of its advantages to be brought out and illustrate some of itsimplementation variants.

EXAMPLES AND TESTS

Structures

-   -   resin sold by the company Dow Chemical under the reference        ERLX-4360 (resin of the family described under the structure        S-104 mentioned above),    -   filler (B-1): quartz glass (particle size=1.5 μm, SiO₂ 56%; SrO        14%; B₂O₃ 14%; Al₂O₃ 14%; F 2%) sold by the company Schott under        the reference G018-163    -   filler (B-2): quartz glass (particle size 1.5 μm, SiO₂ 55%; BaO        25%; B₂O₃ 10%; Al₂O₃ 10%) sold by the company Schott under the        reference GM27-884.

Preparation of a Thioxanthone Containing Ammonium Borate Functionality(S-61)

1.02 g of3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-2-hydroxypropyl)trimethylammoniumchloride (sold by the company Aldrich); 2.688 g of “Kisbore” saltKB(C₆F₅)₄ (prepared by the company Rhodia) and 50 ml of isopropanol areintroduced, protected from light, into an opaque flask and the mixtureis left under magnetic stirring for 48 hours at room temperature. Themixture is then poured into demineralized water (200 ml). A yellowprecipitate forms. The suspension is filtered through a Büchner funneland the solid is dried for 24 hours in an oven at 100° C. The saltreferenced (PS-31) is obtained (melting point 235° C.; absorptionmaximum λmax=397.3 nm).

EXAMPLE 1 (Comparative): Treatment of the Filler (B-1)

a) Treatment of the Filler with a Coupling Agent Containing DiolFunctionality (F-2):

The silane glycidyloxypropyltrimethoxysilane or GLYMO

of formula (F-1) sold by the company Degussa is hydrolyzed in acidicmedium according to the following reaction:

-   -   with R=methyl

The compound (F-2) is in a more or less polycondensed form and issoluble in aqueous phase.

The solution used is a solution containing 40% silane (F-2) with apH=3-4.

12.5 g of this 40% solution of silane (F-2) are poured into a beaker andmade up with 200 g of demineralized water. 200 g of filler (B-1) arepoured into this solution and the mixture is stirred for 1 hour at roomtemperature using an impeller stirrer. The mixture is poured into acrystallizing dish and the filler is dried in an oven for 16 hours at150° C. The filler is then screened through a 250 micron gauze.

b) Treatment with a Coupling Agent Containing Oxirane Functionality

For comparative purposes, we performed the hydrolysis of the silaneglycidyloxypropyltrimethoxysilane in neutral medium and we removed themajority of the methanol arising from the hydrolysis reaction bydistillation. Analysis by ¹H NMR reveals that the epoxide function isnot hydrolyzed when this solution is cold-stored for several weeks.

A 40% solution of silane (F-3) at pH=7 is used.

12.5 g of this 40% solution are poured into a beaker and made up with200 g of demineralized water. 200 g of untreated filler (B-1) are pouredinto this solution and the mixture is stirred for 1 hour at roomtemperature using an impeller stirrer. The mixture is poured into acrystallizing dish and the filler is dried in an oven for 16 hours at150° C. The filler is then screened through a 250 micron gauze.

c) Properties of the Dental Compositions

11.625 g of siloxane resin containing an oxirane function (S-1) areplaced in a centrifugal mixer (Hauschild brand).

1.125 g of a 4% solution of dispersant (C-1) (sold by the company Bykunder the reference Disperbyk-164®) are added. The mixture is stirredfor 16 seconds using the centrifugal mixer at 3000 rpm, and 3 g ofytterbium trifluoride are added. The mixture is stirred for a further 16seconds with the centrifugal mixer at 3000 rpm, and 1.25 g ofphotoinitiator system (P) containing 30% by weight of photoinitiator(P-22) and 0.89% by weight of the photosensitizer of formula (PS-31) asa solution in (S-1) are then added.

The mixture is stirred for 16 seconds with the centrifugal mixer at 3000rpm, at room temperature, and 25 g of the filler (B-1) are then added:

-   -   untreated (formulation 1t),    -   or treated according to a) (formulation 1a);    -   or treated according to b) (formulation 1b).

The mixture is stirred for 16 seconds with the centrifugal mixer. 3grams of a filler of combustion silica type (B-3) (SiO₂>99%, sold by thecompany Degussa under the reference OX50®) are added and the mixture isthen stirred for 16 seconds. Finally, 5 g of a filler of combustionsilica type (B-4) sold by the company Degussa under the reference R202®are finally added, and the mixture is then stirred for 16 seconds.

The change in viscosity over time is monitored for the threeformulations. The moment at which the formulation of the composite isgelled and is no longer manipulable is noted. The results are given inTable 1. TABLE 1 Comparative Stability at 25° C. Formulation 1t <24 hFormulation 1a <24 h Formulation 1b  48 h

EXAMPLE 2 Invention

a) Treatment with the Resin Containing an Oxirane Function (S-1) of theFillers Obtained in Example 1a)

A solution containing 2.5% by weight of resin containing an oxiranefunction (S-1) is prepared in acetone.

100 g of filler (B-1) treated according to Example 1a) are poured onto100 g of this 2.5% solution and stirred mechanically at room temperaturefor about one minute. The mixture is then poured into a crystallizingdish and the acetone is evaporated off at room temperature.

The residue is heated at 150° C. for 16 hours in order to polymerize theresin containing an oxirane function (S-1) at the surface of the filler.The filler is then screened to obtain a powder.

b) Treatment with the Resin Containing an Oxirane Function (S-1) of theFillers Obtained in Example 1b)

A solution containing 2.5% by weight of resin containing an oxiranefunction (S-1) is prepared in acetone.

100 g of filler (B-1) treated according to Example 1b) are poured onto100 g of this 2.5% solution and stirred mechanically at room temperaturefor about one minute. The mixture is then poured into a crystallizingdish and the acetone is evaporated off at room temperature. The residueis heated at 150° C. for 16 hours in order to polymerize the resincontaining an oxirane function (S-1) at the surface of the filler. Thefiller is then screened to obtain a powder.

c) Properties of the Dental Compositions

The two fillers of Examples 2-a) and 2-b) are formulated in the same wayas in Example 1-c), the overall filler content is 72% by weight relativeto the weight of the composition, to obtain two dental compositions(formulations (2a) and (3b), respectively), the stability and the changeover time of which are monitored. TABLE 2 Stability at InventionTreatment 25° C. Formulation a) solution containing 2.5% by 1 month (2a)weight of resin (S-1) Formulation b) solution containing 2.5% by 1 week(2b) weight of resin (S-1)

Comparison of the results between:

-   -   formulations (1a) and (2a), and    -   formulations (1b) and (2b) shows a marked improvement in        stability.

EXAMPLE 3 Invention, Double Treatment of the Filler

Variation of the Content of Resin Containing an Oxirane Function (S-1)

Example 2a) is repeated, varying the content of resin containing anoxirane function (S-1) during the treatment of the filler (B-1).

A dental composition is then formulated as in Example 2c).

The exact composition corresponds to the following formulation (theoverall filler content is 66% by weight relative to the weight of thecomposition): resin containing an oxirane --------> 29.25 g function(S-1) dispersant solution containing --------> 2.25 g 4% (C-1)photoinitiator system (P) (see --------> 2.5 g Example 1): (P-22) +(PS-31) ytterbium trifluoride --------> 6 g double-treated filler (B-1)--------> 50 g untreated filler (B-3) --------> 5 g combustion silicaOX50 ® untreated filler (B-4) --------> 5 g combustion silica R202 ®

The change in the epoxy content is monitored by potentiometric assay insolution of the composite in the perchloric acid assay solution. TABLE 3% by weight of the resin (S-1) in acetone for Degree of the treatment ofconversion of Stability at Dental the filler the epoxy % 25° C.compositions (B-1): after 26 days (months) Control 0 not 0 formulation(1t) measurable Formulation (3a) 1 23 1 Formulation (3b) 2.5 19 3Formulation (3c) 5 16 >12 months

EXAMPLE 4 Invention, Double Treatment of the Filler

Preparation of a Dental Composition with an Overall Filler Content of70% by Weight Relative to the Weight of the Composition.

11.5 g of siloxane resin containing an oxirane function (S-1) are placedin a Hauschild centrifugal mixer. 2.25 g of a 4% solution of dispersant(C-1) sold by the company Byk under the reference Disperbyk-164® areadded. The mixture is stirred for 16 seconds with the centrifugal mixerat 3000 rpm, and 3 g of ytterbium trifluoride are added. The mixture isstirred for a further 16 seconds with the centrifugal mixer at 3000rpm;, and 1.25 g of a photoinitiator system (P) containing 30% by weightof photoinitiator (P-22) and 0.89% by weight of photosensitizer based on(PS-31) are then added to the resin (S-1). The mixture is stirred for 16seconds with the centrifugal mixer at 3000 rpm and at room temperature,and 27 g of the filler (B-1) treated according to Example 2a) and thenaccording to Example 3 (treatment of the filler (B-1) with a solutioncontaining 5% by weight of the resin (S-1) in acetone) are then added.The mixture is stirred for 16 seconds with the centrifugal mixer. 2.5 gof combustion silica (B-3) (sold by the company Degussa under thereference OX50®, SiO₂>99%) treated as for the filler (B-1) are added andthe mixture is then stirred for 16 seconds. Finally, 2.5 g of combustionsilica (B-4) (sold by the company Degussa under the reference R202®) areadded and the mixture is stirred for 16 seconds.

The change in viscosity over time is monitored for the formulation withtreated fillers. This formulation is stable for more than 1 year at 25°C.

Samples as described in standard ISO 4049 are crosslinked using ahalogen lamp of Demetron Optilux 500 type (irradiation time: 2 times 40seconds).

The flexural strength measured according to standard ISO-4049 is 90 Mpa±10 with a bending modulus of 9000 MPa.

The depth of crosslinking is 4 mm after irradiation for 40 seconds.

The volume shrinkage calculated from the densities measured before andafter polymerization is: −1.6% ±0.2.

The exact composition corresponds to the following formulation (theoverall filler content is 70% by weight relative to the weight of thecomposition): resin containing an oxirane --------> 11.5 g function(S-1) dispersant solution (C-1) --------> 2.25 g photoinitiator system(P): --------> 1.25 g (P-22) + (PS-31) treated ytterbium trifluoride--------> 3 g double-treated filler (B-1) --------> 27 g untreatedfiller (B-3) --------> 2.5 g combustion silica OX50 ® untreated filler(B-4) --------> 2.5 g combustion silica R202 ®

EXAMPLE 5 Invention, Double Treatment of the Filler

The impact of the nature of the photosensitizers on the coloration ofthe composition after irradiation with a dentistry lamp was compared.Example 4 was reproduced, modifying the nature and amount ofphotosensitizer introduced into the composition.

The dental compositions described in Examples 2 to 5 are crosslinked toa thickness of 2 to 3 mm with an irradiation time of between 30 secondsand 1 minute using an Optilux Demetron lamp. The values L*,a*,b* aremeasured using a Minolta CR200 chromameter or calorimeter, after 15minutes of crosslinking on a white background and after 5 days ofcrosslinking.

The chromatic difference obtained Δc defined such thatΔc=[(Δa)²+(Δb)²]^(1/2), is deduced therefrom.

It is found that the crosslinking with a Demetron Optilux 500 dentistrylamp of the dental compositions formulated with the photosensitizer(PS-31), alone or in combination with other photosensitizers, forexample (PS-39); (PS-34) and (PS-33), does not give rise to anycoloration defect (no phenomenon of reddening during irradiation with achromatic value a>1 immediately after irradiation). TABLE 4 Photo-Concentra- T = 15 minutes; L, a, b T = 5 days; L, a, b Examplesensitizer (s) tion(s) ppm L* a* b* L* a* b* Δc 5-a PS-47  67 69.15 2.877.68 73.4 −0.5 9.55 3.85 5-b PS-30 220 71.1 1.70 16.2 75.85 −1.51 14.753.5 5-c PS-31 220 76.35 0.29 12.4 78.06 −0.63 11.9 1.08 5-d PS-31 17072.8 1.01 10.02 75.24 −0.4 8.73 1.51 5-e PS-31; PS-39 170; 130 73.4 0.4614.16 76.47 −1.0 13.04 1.84 5-f PS-31; PS-34; 170; 100; 120 70.1 −0.2115.68 73.69 −1.33 13.94 2.07 PS-39 5-g PS-31; PS-33; 170; 50; 110 69.081.41 15.58 73.42 −0.79 15.07 2.26 PS-39 5-h PS-34; PS-39 100; 160Kinetics insufficient for crosslinking in 1 minute to 3 mm

The use of the combination of thioxanthone (PS-31) makes it possible toeliminate the coloration problems, but also the kinetic problemsencountered by using camphorquinone (PS-34) alone or camphorquinone incombination with the anthracene derivative (PS-39) in low concentration(of less than 0.1% in the case of Example 5-h).

EXAMPLE 6 Invention, Double Treatment of the Filler

Example 5 is repeated, replacing:

-   -   the photoinitiator (P-22) with the photoinitiator (P-29); and    -   the photoinitiator system (P) with the photoinitiator system        (P′) containing 30% by weight of photoinitiator (P-29) and 0.89%        by weight of photosensitizer based on (PS-31) in the resin        (S-1).

Chromatic difference:

-   -   after 15 minutes of crosslinking on a white background,        L*,a*,b*=72.1; +0.10; 9.53 respectively; and    -   after 5 days, L*,a*,b*=75; −0.25; 8.1, respectively.    -   =>Δc=[(Δa)²+(Δb)²]^(1/2)=1.47.

EXAMPLE 7 Invention, Double Treatment of the Filler

a) Treatment of the Filler (B-2) with Glycidyloxypropyltrimethoxysilane

300 g of an acetone solution containing 2.5% ofglycidyloxypropyltrimethoxysilane are introduced under nitrogen onto 300g of glass B-2. The mixture is then stirred vigorously using aTeflon-coated impeller for 8 hours at room temperature. The “slurry” isthen filtered to recover the glass and the filter cake is screenedthrough a 200-micron gauze. The screened glass is air-dried at 110° C.for 8 hours.

b) Treatment of the Filler (B-2) Obtained from Example 7-a) with theMixture of Resins (S-1) and (S-104) Containing Oxirane Functionality.

300 g of a solution in acetone containing 3.8% of (S-1) and 3.8% of(S-104) are introduced onto 300 g of glass treated according to Example7-a) and the mixture is then stirred under nitrogen using aTeflon-coated impeller for 8 hours at room temperature.

The glass is filtered through a polyamide filter and then screenedthrough a 200-micron gauze and finally dried at 110° C. for 12 hours.

The treated glass obtained (double-treated filler) is then used to makethe following dental composition (the overall filler content is 75%relative to the total weight of the composition): resin containing anoxirane function (S-1) 4.5 g resin containing oxirane functionality 4.5g (S-104) dispersant solution (C-1) 2.25 g photoinitiator system (P):(P22) + (PS-31) 1.25 g double-treated filler [B-2] 32.5 g double-treatedfiller (B-3), combustion 2.5 g silica OX50 ® untreated filler (B-4),combustion silica 2.5 g R202 ®

The change in the epoxy content over time of the composition ismonitored. It is observed that the composition is stable for at least 9months at 25° C. with a degree of conversion of the epoxys of less than20%.

Samples as described in standard ISO 4049 are crosslinked using aDemetron Optilux 500 halogen lamp (irradiation time: 2 times 40seconds).

The bending strength measured according to standard ISO-4049 is 90 Mpa±10 with a bending modulus of 800 MPa ±1000.

The depth of crosslinking is 4 mm after irradiation for 40 seconds.

The volume shrinkage calculated from the densities measured before andafter polymerization is −1.4% ±0.2.

EXAMPLE 8 Invention, Double Treatment of the Filler

The treated glass (double-treated filler) obtained according to Example7b) is then used to make the following dental composition (the overallfiller content is 75% relative to the total weight of the composition):resin containing an oxirane function (S-1) 4.5 g resin containingoxirane functionality 4.5 g (S-104) dispersant solution (C-1) 2.25 gphotoinitiator system (P): (P22) + (PS-31) 1.25 g double-treated filler[B-2] 32.5 g double-treated filler (B-3), combustion 2.5 g silica OX50 ®untreated filler (B-5), colloidal silica 2.5 g as a solution at aconcentration of about 40% by weight in a resin (S-96) sold by thecompany Hanse Chemie

The change in the epoxy content over time of the composition ismonitored. It is observed that the composition is stable for at least 9months at 25° C. with a degree of conversion of the epoxys of less than20%.

Samples as described in standard ISO 4049 are crosslinked using aDemetron Optilux 500 halogen lamp (irradiation time: 2 times 40seconds).

The bending strength measured according to standard ISO-4049 is 100 MPa±10 with a bending modulus of 8000 MPa ±1000.

The depth of crosslinking is 4 mm after irradiation for 40 seconds.

The volume shrinkage calculated from the densities measured before andafter polymerization is −1.4 ±0.2.

1. A dental composition comprising: (1) at least one cationicallyreactive compound (A); (2) at least one dental filler (B); (3)optionally at least one dispersant (C) comprising at least one organicpolymer or copolymer; (4) at least one cationic photoinitiator (D); (5)and optionally at least one photosensitizer (E), wherein said at leastone dental filler (B) is treated: a) with at least one organosiliconcoupling agent (F) and b) with at least one compound (G), saidorganosilicon coupling agent (F) comprising at least one reactivefunction (rfA) directly linked to a silicon atom reacting with thedental filler, and at least one reactive function (rfB) not directlylinked to a silicon atom reacting with a reactive function (rfC) of thecompound (G).
 2. The dental composition as claimed in claim 1, in which:the reactive function (rfA) directly linked to a silicon atom of theorganosilicon coupling agent (F) is an alkoxy, enoxy or hydroxylfunction; the reactive function (rfB) not directly linked to a siliconatom of the organosilicon coupling agent (F) is an oxirane, oxetane,hydroxyl, acid, carboxylic acid anhydride or diol function; and thereactive function (rfC) of the compound (G) is an oxirane, oxetane,alkenyl ether or carbonate function.
 3. The dental composition asclaimed in claim 1, in which at least one dental filler (B) is treatedvia a process (I) comprising the following steps: a) the dental filler(B) and at least one organosilicon coupling agent (F) comprising atleast one alkoxy, enoxy and/or hydroxyl function directly linked to asilicon atom and at least one oxirane, oxetane, hydroxyl, acid,carboxylic acid anhydride and/or diol function are mixed together insolvent medium, b) the solvent is evaporated off to obtain anintermediate dental filler (B-1), c) the intermediate dental filler(B-1) undergoes a heat treatment so as to allow the coupling reactionbetween the intermediate dental filler (B-1) and the coupling agent (F)and thus to obtain an intermediate dental filler (B-2), d) theintermediate dental filler (B-2) is next mixed in solvent medium with atleast one compound (G) comprising at least one oxirane, oxetane, alkenylether and/or carbonate function, e) the solvent is evaporated off toobtain an intermediate dental filler (B-3), and f) the intermediatedental filler (B-3) undergoes a heat treatment so as to allow thereaction between the intermediate dental filler (B-3) and the compound(G) and thus to obtain a treated dental filler (B-4).
 4. The dentalcomposition as claimed in claim 3, in which the heat treatment of stepsc) and f) of the process (I) is performed by heating to a temperature ofless than or equal to 200° C.
 5. The dental composition as claimed inclaim 1, in which the overall content of dental fillers (B) representsup to 85% by weight and relative to the total weight of the dentalcomposition.
 6. The dental composition as claimed in claim 1, in whichthe treatment of the dental filler (B) is performed with up 20% byweight of the compound (G) and/or up to 20% by weight of the compound(F) relative to the total weight of the dental composition.
 7. Thedental composition as claimed in claim 1, in which the organosiliconcoupling agent (F) is of the formula:

in which formula: R is a hydrogen or a linear or branched C₁-C₄ alkylradical, R¹ is a linear or branched alkyl radical or a phenyl radical, xis equal to 0, 1 or 2, and X being defined by one of the followingformulae:

with: E and D which are identical or different radicals chosen fromlinear or branched C₁-C₁₂ alkyls, z is equal to 0 or 1; n is equal to 0or 1; is equal to 0, 1, 2, 3, 4, 5 or 6; R², R³, R⁴, R⁵, R⁶, R⁷ and R⁸are radicals, which may be identical or different, representing ahydrogen or a linear or branched C₁-C₁₂ alkyl.
 8. The dental compositionas claimed in claim 7, in which the organosilicon coupling agent (F) ischosen from the group consisting of the following compounds:glycidyloxypropyltrimethoxysilane, the product of hydrolysis ofglycidyloxypropyltrimethoxysilane; glycidyloxypropyltriethoxysilane, theproduct of hydrolysis in acidic medium ofglycidyloxypropyltriethoxysilane; glycidyloxypropyldimethoxymethylsilaneand its hydrolysis product, β-(3,4-epoxycyclohexyl)ethyltriethoxysilaneand its hydrolysis product, andβ-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and its hydrolysis product.9. The dental composition as claimed in claim 1, in which the compound(G) is an organic or organosiloxane monomer, oligomer or polymercomprising at least one oxirane, oxetane, alkenyl ether and/or carbonatefunction.
 10. The dental composition as claimed in claim 9, in which thecompound (G) comprises at least one function chosen from the groupconsisting of the structures (M-7) to (M-12) below:

with R″ representing a linear or branched C₁-C₆ alkyl radical.
 11. Thedental composition as claimed in claim 9, in which the compound (G) is asilicone oligomer (G-1) or a silicone polymer (G-2).
 12. The dentalcomposition as claimed in claim 11, in which the silicone oligomer (G-1)and the silicone polymer (G-2) comprise: a) at least one unit offormula:

in which formula: a=0, 1 or2, R⁰, which may be identical or different,represents an alkyl, cycloalkyl, aryl, vinyl, hydrogeno or alkoxyradical, Z, which may be identical or different, is an organicsubstituent comprising at least one oxirane, alkenyl ether, oxetaneand/or carbonate function, and b) at least two silicon atoms.
 13. Thedental composition as claimed in claim 12, in which the siliconeoligomer (G-1) and the silicone polymer (G-2) are chosen from the groupconsisting of the compounds of formulae:

L=H; OH; Me; Phenyl; C₁-C₁₂ Alkyl; C₁-C₆ Cycloalkyl; or the followinggroups

with n<100; a<100 and m<100: and o)

with n<100(S-15) in which formulae R^(o) or R₀, which may be identical ordifferent, represents an alkyl, cycloalkyl or aryl radical.
 14. Thedental composition as claimed in claim 1, wherein the cationicallyreactive compound (A) is chosen from the group of monomers and/or(co)polymers selected from the group consisting of: epoxys, vinylethers, oxetanes, spiroorthocarbonates and spiroorthoesters, andcombinations thereof.
 15. The dental composition as claimed in claim 14,in which the cationically reactive compound (A) comprises at least onecrosslinkable and/or polymerizable silicone oligomer (G-1) or siliconepolymer (G-2), which is liquid at room temperature or thermofusible at atemperature below 100° C., and comprising: a) at least one unit havingthe following formula:

in which formula: a=0, 1 or 2, R⁰, which may be identical or different,represents an alkyl, cycloalkyl, aryl, vinyl, hydrogeno or alkoxyradical, Z, which may be identical or different, is an organicsubstituent comprising at least one oxirane, alkenyl ether, oxetane,dioxolane and/or carbonate function, and b) at least two silicon atoms.16. The dental composition as claimed in claim 15, wherein the unit(M-13) comprises groups Z chosen from the group consisting of theradicals (R-1) to (R-9) below:

with R″ representing a linear or branched C₁-C₆ alkyl radical.
 17. Thedental composition as claimed in claim 13, wherein the cationicallyreactive compound (A) is chosen from the group consisting of thecompounds (S-1) to (S-15).
 18. The dental composition as claimed inclaim 1, wherein the cationic photoinitiator (D) is a borate and ischosen from those of the following formula in which: a) the cationicspecies of the borate is selected from the group consisting of: (1) theonium salts of formula:[(R⁹)_(n)-A-(R¹⁰)_(m)]⁺  (I) in which formula: A represents an elementfrom groups 15 to 17, R⁹ represents a C₆-C₂₀ carbocyclic or heterocyclicaryl radical, said heterocyclic radical optionally containing nitrogenor sulfur as hetero elements, R¹⁰ represents R⁹ or a linear or branchedC_(1-C) ₃₀ alkyl or alkenyl radical; said radicals R⁹ and R¹⁰ beingoptionally substituted with a C₁-C₂₅ alkoxy, C₁-C₂₅ alkyl, nitro,chloro, bromo, cyano, carboxyl, ester or mercapto group, m and n areintegers, with n+m=v+1, v being the valency of the element A, (2)oxoisothiochromanium salts; and (3) organometallic salts having thefollowing formula:(L₁L₂L₃M)^(+q)   (II) in which formula: M represents a metal from groups4 to 10, L1 represents a ligand linked to the metal M via π electrons,the ligand being chosen from the ligands η³-alkyl, η⁵-cyclopentadienyland η⁷-cycloheptatrienyl and the η⁶-aromatic compounds chosen from theoptionally substituted η⁶-benzene ligands and the compounds containingfrom 2 to 4 fused rings, each ring being capable of contributing to thevalency layer of the metal M via 3 to 8 π electrons, L2 represents aligand linked to the metal M via π electrons, the ligand being chosenfrom the η⁷-cycloheptatrienyl ligands and the η⁶-aromatic compoundschosen from the optionally substituted η⁶-benzene ligands and thecompounds containing from 2 to 4 fused rings, each ring being capable ofcontributing to the valency layer of the metal M via 6 or 7 π electrons,L3 represents from 0 to 3 identical or different ligands linked to themetal M via σ electrons, this or these ligand(s) being chosen from COand NO₂+; the total electronic charge q of the complex toward which L1,L2 and L3 contribute and the ionic charge of the metal M being positiveand equal to 1 or 2; and b) the anionic borate species of the formula:[BX_(a)R_(b)]⁻  (III) in which formula: a and b are integers ranging fora from 0 to 3 and for b from 1 to 4 with a+b =4, the symbols Xrepresent: a halogen atom with a=0 to 3, or an OH function with a=0 to2, the symbols R are identical or different and represent: a phenylradical substituted with at least one electron-withdrawing group, and/orwith at least 2 halogen atoms, this being the case when the cationicspecies is an onium of an element from groups 15 to 17, a phenyl radicalsubstituted with at least one element or an electron-withdrawing group,this being the case when the cationic species is an organometalliccomplex of an element from groups 4 to 10, or an aryl radical containingat least two aromatic nuclei, optionally substituted with at least oneelement or an electron-withdrawing group, irrespective of the cationicspecies.
 19. The composition as claimed in claim 18, wherein thecationic photoinitiator (D) is chosen from the group consisting of thefollowing compounds: (P-16): [(C₈H₁₇)—O—C₆H₄—I—C₆H₅)]⁺, [B(C₆F₅)₄]⁻;(P-17): [C₁₂H₂₅—C₆H₄—I—C₆H₅]⁺, [B(C₆F₅)₄]⁻; (P-18): [(C₈H₁₇—O—C₆H₄)₂]⁺,[B(C₆F₅)₄]⁻; (P-19): [(C₈H₁₇)—O—C₆H₄—I—C₆H₅)]⁺, [B(C₆F₅)₄]⁻; (P-20):[(C₆H₅)₂S—C₆H₄—O—C₈H₁₇]⁺, [B(C₆H₄CF₃)₄]⁻; (P-21): [(C₁₂H₂₅—C₆H₄)₂I]⁺,[B(C₆F₅)₄]⁻; (P-22): [CH₃—C₆H₄—I—C₆H₄—CH(CH₃)₂ ⁺, [B(C₆F₅)₄]⁻; (P-23):(η5-cyclopentadienyl)(η6-toluene)Fe⁺, [B(C₆F₅)₄]⁻; (P-24):(η5-cyclopentadienyl)(η6-methyl-1-naphthalene)Fe⁺, [B(C₆F₅)₄]⁻; (P-25):(η5-cyclopentadienyl)(η6-cumene)Fe⁺, [B(C₆F₅)₄]⁻; (P-26):[(C₁₂H₂₅—C₆H₄)₂]⁺, [B(C₆H₃(CF₃)₂]⁻; (P-27):[CH₃—C₆H₄—I—C₆H₄—CH₂CH(CH₃)₂]⁺, [B(C₆F₅)₄]⁻; (P-28):[CH₃—C₆H₄)—I—C₆H₄—CH₂CH(CH₃)₂]⁺, [B(C₆H₃(CF₃)₂)₄]⁻; and (P-29):[CH₃—C₆H₄—I—C₆H₄—CH(CH₃)₂]⁺, [B(C₆H₃(CF₃)₂)₄]⁻.
 20. The dentalcomposition as claimed in claim 1, wherein the cationic photoinitiator(D) is an iodonium salt.
 21. The dental composition as claimed in claim1, in which the photosensitizer (E) comprises in its structure one ormore substituted or unsubstituted aromatic nuclei having a residuallight absorption of between 200 and 500 nm.
 22. The dental compositionas claimed in claim 21, in which the photosensitizer (E) is chosen fromthe group consisting of compounds of the anthracene, thioxanthone,camphorquinone and phenanthrenequinone class, and also mixtures thereof.23. The dental composition as claimed in claim 22, in which thephotosensitizer (E) is a salt of a thioxanthone substituted with atleast one group comprising an ammonium function.
 24. The dentalcomposition as claimed in claim 23, wherein the associated anion of thesalt of the thioxanthone substituted with at least one group comprisingan ammonium function is chosen from the following anions: a halide, BF₄⁻, PF₆ ⁻; SbF₆ ⁻; the anion (III) of formula [BX_(a)R_(b)]⁻ defined asclaimed in claim 18, R_(f)SO₃ ⁻; (R_(f)SO₂)₃C⁻ or (R_(f)SO₂)₂N⁻ withR_(f) being a linear or branched alkyl radical substituted with at leastone halogen atom.
 25. The dental composition as claimed in claim 1, inwhich the photosensitizer (E), optionally in combination with at leastone camphorquinone, a phenanthrenequinone and/or a substitutedanthracene, has the formula:

in which formula: R²² and R²³ are identical or different and represent ahydrogen or an optionally substituted C₁-C₁₀ alkyl radical, (X⁻) beingan anionic species, the anion (III) of formula [BX_(a)R_(b)]⁻ defined asclaimed in claim 16, R_(f)SO₃ ⁻; (R_(f)SO₂)₃C⁻ or (R_(f)SO₂)₂N⁻, withR_(f) being a linear or branched alkyl radical substituted with at leastone halogen atom,
 26. The dental composition as claimed in claim 1, inwhich the photosensitizer (E), optionally in combination with at leastone camphorquinone, a phenanthrenequinone and/or a substitutedanthracene, has the formula:


27. The dental composition as claimed in claim 1, in which thephotosensitizer (E) is chosen from the group consisting of the followingcompounds: (PS-30):3-(3,4-dimethyl-9-oxo-9-thioxanthenen-2-yloxy)-2-hydroxypropyl)trimethylammoniumchloride; (PS-31):3-(3,4-dimethyl-9-oxo-9-thioxanthenen-2-yloxy)-2-hydroxypropyl)trimethylammoniumtetrakis(pentafluorophenyl)borate; (PS-32):3-(3,4-dimethyl-9-oxo-9-thioxanthenen-2-yloxy)-2-hydroxypropyl)trimethylammoniumtetrakis(bis(trifluoromethyl)phenyl)borate; (PS-33):phenanthrenequinone; (PS-34): camphorquinone; (PS-35):acenaphthenequinone; (PS-36): dibenzoyl peroxide; (PS-37):2-ethyl-9,10-dimethoxyanthracene; (PS-38): 9,10-diethoxyanthracene;(PS-39): 9,10-dibutoxyanthracene; (PS-40): 9-hydroxymethylanthracene;(PS-41): 2-dimethylaminothioxanthone; (PS-42):3-ethylcarboxy-7-methoxythioxanthone; (PS-43):1-phenylthio-4-propoxythioxanthone; (PS-44): 2-methoxythioxanthone;(PS-45): 2-(N,N-diethylaminopropoxy)thioxanthone; (PS-46):2-isopropylthioxanthone; (PS-47): 1-chloro-4-propoxythioxanthone;(PS-48): 4-isopropylthioxanthone;

and mixtures thereof.
 28. The dental composition as claimed in claim 1,in which the photosensitizer (E) is chosen from the group consisting ofthe compounds of the coumarin, diketone, fluorone, amino ketone andpara-aminostyryl ketone family, and also mixtures thereof.
 29. Thedental composition as claimed in claim 11, in which the silicone polymer(G-2) or the silicone oligomer (G-1) is combined with an organic epoxyor oxetane resin of formula (S-103) or (S-104):

with: 0≦n≦100 and D=radical chosen from linear or branched C₁-C₁₂alkyls.
 30. The dental composition as claimed in claim 1, in which thedental filler (B) is a mineral glass or a combustion silica.
 31. Thedental composition as claimed in claim 1, in which the compound (G) is asilane (G-3) of formula:

in which formula:E=—CH₂—; —CH═;

R, which may be identical or different, represents an alkyl, cycloalkyl,aryl, vinyl, hydrogeno or alkoxy radical, Z, which may be identical ordifferent, is an organic substituent comprising at least one oxirane,alkenyl ether, oxetane and/or carbonate function, and −a+b=3.
 32. Thedental composition as claimed in claim 31, in which the silane (G-3) ischosen from the group consisting of the following molecules:


33. The dental composition as claimed in claim 1, in which the compound(G) is an organic compound (G-4) chosen from the group consisting of themolecules:

in which formulae: n is an integer between 1 and 10 (limits inclusive);

with n<100 and D=linear or branched C₁-C₁₂ alkyl; and

with n<100 and the group D=linear or branched C₁-C₁₂ alkyl.
 34. Aprocess for treating a reinforcing filler, which comprises treating thefiller: a) with at least one organosilicon coupling agent (F), and b)with at least one compound (G), said organosilicon coupling agent (F)comprising at least one reactive function (rfA) directly linked to asilicon atom reacting with the dental filler, and at least one reactivefunction (rfB) not directly linked to a silicon atom reacting with areactive function (rfC) of the compound (G).
 35. The process fortreating a reinforcing filler, as claimed in claim 34, in which: thereactive function (rfA) directly linked to a silicon atom of theorganosilicon coupling agent (F) is an alkoxy or hydroxyl function; thereactive function (rfB) not directly linked to a silicon atom of theorganosilicon coupling agent (F) is an oxirane, oxetane, hydroxyl, acid,carboxylic acid anhydride or diol function; and the reactive function(rfC) of the compound (G) is an oxirane, oxetane, alkenyl ether orcarbonate function.
 36. The process for treating a reinforcing filler asclaimed in claim 34, comprising the following steps: a) the reinforcingdental filler (B) and at least one organosilicon coupling agent (F)comprising at least one alkoxy and/or hydroxyl function directly linkedto a silicon atom and to at least one oxirane, oxetane, hydroxyl and/ordiol function, are mixed together in solvent medium, b) the solvent isevaporated off to obtain an intermediate dental filler (B-1), c) theintermediate dental filler (B-1) is subjected to a heat treatment so asto allow the coupling reaction between the intermediate dental filler(B-1) and the coupling agent (F) and thus to obtain an intermediatedental filler (B-2), d) the intermediate dental filler (B-2) is thenmixed in solvent medium with at least one compound (G) comprising atleast one oxirane, oxetane, alkenyl ether and/or carbonate function, e)the solvent is evaporated off to obtain an intermediate dental filler(B-3), and f) the intermediate dental filler (B-3) is subjected to aheat treatment so as to allow the reaction between the intermediatedental filler (B-3) and the compound (G) and thus to obtain a treateddental filler (B-4).
 37. The process for treating a reinforcing filleras claimed in claim 36, in which the heat treatment of steps c) and f)of the process (I) is performed by heating to a temperature of less thanor equal to 200° C.
 38. The process for treating a reinforcing filler inwhich an organosilicon coupling agent (F) is used as defined as in claim7.
 39. The process for treating a reinforcing filler in which a compound(G) is used as defined in claim
 10. 40. The process for treating areinforcing filler claim 34, in which the reinforcing filler is amineral glass or a combustion silica.
 41. A reinforcing filler obtainedvia the process as claimed in claim
 34. 42. (canceled)
 43. A dentalprosthesis obtained by crosslinking of a composition as claimed inclaim
 1. 44. Dental restoration material obtained by crosslinking of acomposition as claimed in claim 1.